1. Field of the Invention
The present invention relates to a vacuum release device for assisting removal of plastic bags from containers.
2. Related Art
Removal of plastic bags from containers (e.g. removal of plastic liners from trash cans) is difficult due to vacuum conditions inside the containers. The vacuum conditions are created between the plastic bags and walls of the containers when the plastic bags are placed into the containers and filled. The vacuum conditions may cause rupture of the plastic bags when the filled bags are lifted from the containers. It is desired that the vacuum conditions in the containers can be eliminated or prevented.
In U.S. Pat. No. 4,294,379 (Bard, 1981), a trash receptacle with molded or attached hollow tubes is presented. In U.S. Pat. No. 5,170,906 (Kocheleck, 1992), a trash can with spaced vertical ribs on sidewalls is disclosed. In U.S. Pat. No. 5,375,732 (Bowers, et al., 1994), a garbage container including an air conduit molded in the sidewall is disclosed. U.S. Pat. No. 6,015,063 (Poliquin, 2000) discloses a trash can vent system, in which a vent assembly is positioned along the interior sidewall and attached on the can by a secure cap. U.S. Pat. No. 6,474,495 B1 (Frei, 2002) discloses a garbage can with apertures around both the open and closed ends of the can. In U.S. Pat. No. 6,594,876 B1 (Stastny, 2003), a method for modifying an existing trash can is disclosed. As described in this disclosure, one end of an air conduit is extruded outside of the trash can and tied onto the trash can, and the other end placed on the bottom of the trash can. U.S. Pat. No. 6,736,281 B2 (Joseph, 2004) provides a waste receptacle including air baffles formed on the inner sidewalls and the bottom wall of the receptacle. US Pat. Pub. No. 2007/0068947 A1 (Rush, 2007) discloses a molded half-moon-shaped air tube capable of being bonded to a trash can with a self-adhesive tape. U.S. Pat. No. 7,438,199 (Tidrick, 2008) discloses a vacuum release trash container. The sidewall of the vacuum release trash container has open columns between an inner wall and an outer wall. Vacuum release orifices, in communication with the columns, are made on the top rim and on the inner wall near the bottom of the container.
In summary, there are primarily two categories of methods for vacuum release in trash containers. In the first category, improvements of containers are proposed. The improvements include an air conduit built into sidewalls (U.S. Pat. Nos. 5,375,732 and 7,438,199), air baffles or vertical ribs built on inside surfaces of sidewalls (U.S. Pat. Nos. 5,170,906, 6,736,281 B2), and apertures made on sidewalls (U.S. Pat. No. 6,474,495 B1). These improvements have following disadvantages. (1) Complexity and cost of manufacturing these improved containers will increase. (2) These improvements can not solve the problem of vacuum release in currently used containers.
In the second category, methods of adding vent channels or air conduits on existing containers are developed. These methods are presented in four disclosures, U.S. Pat. Nos. 4,294,379, 6,015,063, and 6,594,876 B1, and US Pat. Pub. No. 2007/0068947 A1. Some disadvantages of these methods are as follows. In U.S. Pat. Nos. 4,294,379 and 6,015,063, and US Pat. Pub. No. 2007/0068947, the vent channels or the air conduits are only capable of being positioned along sidewalls in the containers. Because of the structures of the vent channels or the air conduits, it is impossible to position one assembly of the vent channels or the air conduits continuously along both the sidewall and the bottom wall in the containers. In U.S. Pat. No. 6,594,876 B1, an air conduit is positioned on the bottom of a container, but the air conduit has only one opening at the end of the air conduit on the bottom; therefore, the air conduit can not prevent vacuum in most contacting areas between a plastic trash liner and walls of the container. In U.S. Pat. Nos. 6,594,876 B1 and 6,015,063, one of advantages is that the air conduits or the vent channels are extruded outside of the containers. The most significant disadvantage in the four disclosures is that, due to structures of openings in the air conduits or the vent channels, plastic liners can easily block the openings. The blockage will consequently render the air conduits or the vent channels ineffective in preventing or eliminating vacuum in the containers.